Conjugative Pili of Plasmids in Escherichia coli K-12 and Pseudomonas Species

Summary

There are three basic morphological forms of conjugative pili for plasmids transferable to Escherichia coli K-12: thin flexible, thick flexible, and rigid. Plasmids determining rigid pili transfer at least 2000X more efficiently on a solid surface compared with in a liquid. The majority of such plasmids are naturally derepressefor transfer and pilus synthesis. The following Pseudomonas plasmids determine rigid pili: Rmsl48 (IncP-7), TOL (IncP-9), and R91.5 (IncP-10). Several new plasmid-specific bacteriophages have been found to adsorb to the sides or tips of conjugative pili.